Abstract
Investigation was carried out on the diseases of cultured Penaeus semisulcatus at various stages of their life cycle. Major diseases were bacterial necrosis, Vibrio infection, infestation by filamentous bacteria, shell disease, fungal infections (Lagenidium sp. and Fusarium sp.) and protozoan infection. Various antibacterial antifungal and parasiticides were examined to establish effective methods for disease control. Most disease episodes were associated with poor water quality following failure in water supply.